Reworking messaging interface

ethwire/messaging.go

@@ -1,3 +1,5 @@
+// Package ethwire provides low level access to the Ethereum network and allows
+// you to broadcast data over the network.
 package ethwire
 
 import (
@@ -9,11 +11,13 @@ import (
 	"time"
 )
 
-// Message:
+// Connection interface describing the methods required to implement the wire protocol.
-// [4 bytes token] RLP([TYPE, DATA])
+type Conn interface {
-// Refer to http://wiki.ethereum.org/index.php/Wire_Protocol
+	Write(typ MsgType, v ...interface{}) error
+	Read() *Msg
+}
 
-// The magic token which should be the first 4 bytes of every message.
+// The magic token which should be the first 4 bytes of every message and can be used as separator between messages.
 var MagicToken = []byte{34, 64, 8, 145}
 
 type MsgType byte
@@ -68,6 +72,157 @@ func NewMessage(msgType MsgType, data interface{}) *Msg {
 	}
 }
 
+type Messages []*Msg
+
+// The connection object allows you to set up a connection to the Ethereum network.
+// The Connection object takes care of all encoding and sending objects properly over
+// the network.
+type Connection struct {
+	conn            net.Conn
+	nTimeout        time.Duration
+	pendingMessages Messages
+}
+
+// Create a new connection to the Ethereum network
+func New(conn net.Conn) *Connection {
+	return &Connection{conn: conn, nTimeout: 500}
+}
+
+// Read, reads from the network. It will block until the next message is received.
+func (self *Connection) Read() *Msg {
+	if len(self.pendingMessages) == 0 {
+		self.readMessages()
+	}
+
+	ret := self.pendingMessages[0]
+	self.pendingMessages = self.pendingMessages[1:]
+
+	return ret
+
+}
+
+// Write to the Ethereum network specifying the type of the message and
+// the data. Data can be of type RlpEncodable or []interface{}. Returns
+// nil or if something went wrong an error.
+func (self *Connection) Write(typ MsgType, v ...interface{}) error {
+	var pack []byte
+
+	slice := [][]interface{}{[]interface{}{byte(typ)}}
+	for _, value := range v {
+		if encodable, ok := value.(ethutil.RlpEncodable); ok {
+			slice = append(slice, encodable.RlpValue())
+		} else if raw, ok := value.([]interface{}); ok {
+			slice = append(slice, raw)
+		} else {
+			panic(fmt.Sprintf("Unable to 'write' object of type %T", value))
+		}
+	}
+
+	// Encode the type and the (RLP encoded) data for sending over the wire
+	encoded := ethutil.NewValue(slice).Encode()
+	payloadLength := ethutil.NumberToBytes(uint32(len(encoded)), 32)
+
+	// Write magic token and payload length (first 8 bytes)
+	pack = append(MagicToken, payloadLength...)
+	pack = append(pack, encoded...)
+
+	// Write to the connection
+	_, err := self.conn.Write(pack)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (self *Connection) readMessage(data []byte) (msg *Msg, remaining []byte, done bool, err error) {
+	if len(data) == 0 {
+		return nil, nil, true, nil
+	}
+
+	if len(data) <= 8 {
+		return nil, remaining, false, errors.New("Invalid message")
+	}
+
+	// Check if the received 4 first bytes are the magic token
+	if bytes.Compare(MagicToken, data[:4]) != 0 {
+		return nil, nil, false, fmt.Errorf("MagicToken mismatch. Received %v", data[:4])
+	}
+
+	messageLength := ethutil.BytesToNumber(data[4:8])
+	remaining = data[8+messageLength:]
+	if int(messageLength) > len(data[8:]) {
+		return nil, nil, false, fmt.Errorf("message length %d, expected %d", len(data[8:]), messageLength)
+	}
+
+	message := data[8 : 8+messageLength]
+	decoder := ethutil.NewValueFromBytes(message)
+	// Type of message
+	t := decoder.Get(0).Uint()
+	// Actual data
+	d := decoder.SliceFrom(1)
+
+	msg = &Msg{
+		Type: MsgType(t),
+		Data: d,
+	}
+
+	return
+}
+
+// The basic message reader waits for data on the given connection, decoding
+// and doing a few sanity checks such as if there's a data type and
+// unmarhals the given data
+func (self *Connection) readMessages() (err error) {
+	// The recovering function in case anything goes horribly wrong
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("ethwire.ReadMessage error: %v", r)
+		}
+	}()
+
+	// Buff for writing network message to
+	//buff := make([]byte, 1440)
+	var buff []byte
+	var totalBytes int
+	for {
+		// Give buffering some time
+		self.conn.SetReadDeadline(time.Now().Add(self.nTimeout * time.Millisecond))
+		// Create a new temporarily buffer
+		b := make([]byte, 1440)
+		// Wait for a message from this peer
+		n, _ := self.conn.Read(b)
+		if err != nil && n == 0 {
+			if err.Error() != "EOF" {
+				fmt.Println("err now", err)
+				return err
+			} else {
+				break
+			}
+
+			// Messages can't be empty
+		} else if n == 0 {
+			break
+		}
+
+		buff = append(buff, b[:n]...)
+		totalBytes += n
+	}
+
+	// Reslice buffer
+	buff = buff[:totalBytes]
+	msg, remaining, done, err := self.readMessage(buff)
+	for ; done != true; msg, remaining, done, err = self.readMessage(remaining) {
+		//log.Println("rx", msg)
+
+		if msg != nil {
+			self.pendingMessages = append(self.pendingMessages, msg)
+		}
+	}
+
+	return
+}
+
 func ReadMessage(data []byte) (msg *Msg, remaining []byte, done bool, err error) {
 	if len(data) == 0 {
 		return nil, nil, true, nil